CA1076830A - Static friction free altimeter - Google Patents
Static friction free altimeterInfo
- Publication number
- CA1076830A CA1076830A CA291,416A CA291416A CA1076830A CA 1076830 A CA1076830 A CA 1076830A CA 291416 A CA291416 A CA 291416A CA 1076830 A CA1076830 A CA 1076830A
- Authority
- CA
- Canada
- Prior art keywords
- altimeter
- electrical
- piezoelectrical
- recited
- housing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L7/00—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements
- G01L7/02—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges
- G01L7/10—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges of the capsule type
- G01L7/12—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges of the capsule type with exhausted chamber; Aneroid barometers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
- G01C5/06—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels by using barometric means
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Geophysics And Detection Of Objects (AREA)
- General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
- Radar Systems Or Details Thereof (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
- Electromechanical Clocks (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A piezoelectrical transducer for providing an altimeter with vibratory motion to attenuate the effect of static friction on the movement of a gear train responding to an altitude responsive aneroid.
A piezoelectrical transducer for providing an altimeter with vibratory motion to attenuate the effect of static friction on the movement of a gear train responding to an altitude responsive aneroid.
Description
10768~
This invention relates to a vibratory apparatus for attenuating static friction in an altimeter havine an indicator driven by a low power sensor.
Since such low power sensors are responsive to the changes in pressure associated with changes in altitude, it is necessary that each incremen-t of torque developed by these sensors be transmitted to an ou-tput pointer without modifica-tion to assure that indicated altitude is the actual altitude.
Initially, it was thought that the vibrations produced ~ithin an aircraft would be sufficient to prevent static fric-tion. However, from observation it was observed that the indi-cator pointer movement was erratic, especially when the aircraft was operating on a smooth glide path.
Thereafter, it was suggested that a rotating eccentric vibrator or electrically driven thumper be attached to the hous-ing of the altimeter to attenuate static friction. While operating successfully to reduce static friction, such devices produce objectionable noise in the cockpit area of the aircraft, suffer from mechanical wearout, and thus fail to produce uniform results after a limited time period.
We have devised an altimeter with a piezoelectric transducer connected to the gear train of the altimeter which eliminates static friction without the creation of objectionable noise.
The present invention resides in an altimeter having a gear train driven by an altitude responsive member, with means for attenuating the frictional resistance of the gear train. According to the invention there is provided a housing connected to the gear train, the housing having a chamber located therein with a piezoelectrical transducer located in the chamber. Energy control means is provided for supplying the piezoelectrical transducer with cyclic electrical signals, rw~ - 2 - ~ -'` ~
1~)'76830 the cyclic electrical signals causing the physical dimensions of the piezoelectrical transducer to change and to transmit vibratory motion through the housing to the gear train to eliminate the effect of static friction thereon.
In a specific embodiment of the invention, the piezoelectric transducer, which is located in the housing, is encapsulated in a layer of insulating material. The insul-ating material, in addition to preventing the transmission of electrical energy between the pie~oelectric transducer and the housing, absorbs noise caused during the activation of the piezoelectric transducer by a cyclic electrical operational signal.
It is the object of this invention to provide an altimeter with a piezoelectric transducer connected to the gear train to attenuate static friction associated therewi-th.
In one embodiment of this invention there is provided ', an altimeter with a piezoelectric transducer responsive to an !:electrical signal derived from the operation of a four layer ~ ;
transistor diode device for attenuating static friction associa~
ted with a gear train through which a pressure responsive alti-tude sensor supplies an indicator with torque.
. These and other objects should be apparent from reading ~;
this specification and viewing the drawings. ~ ;
` BRIEF DESCRIPTIO~ OF THE DRAWI~G
The single figure in the drawing schematically illus-,- trates an altimeter and associated piezoelectrical transducer made according to the principles of this invention.
DETAILED DESCRIPTION OF THE INVENTION
The altimeter 10 shown in the drawing is similar to the altimeter disclosed in U.S. Patent No. 3,916,185.
The altimeter has a pressure responsive sensor with a first aneroid 12 ancl a second aneroid 13 located in a chamber 1~ of ''' ' ', .. 3~ , ~ rw/~!
- - .. ~ . . .~ . ;
10761~30 a housing 16. The first aneroid 12 is connected to a shaft 18 through an arm 20. Ends 22 and 24 of shaft 18 are journalled in jeweled bearings 26 and 28 which are pressed into openings in housing 16. A sector gear 30, which is fixed to shaft 18, engages gear 32 on the aneroid output shaft 34. The second aneroid 13 is similarly connectecl to a shaft 19 which retains sector gear 36. The outpu-t shaft 34 is carried through opening 38 in wall 40 of housing 16. A clriver gear 44, which is fixed .~ to the end of the output shaft 34, positions a barometric input gear 42 adjacent wall 40. The driver gear 44 is connected to output shaft 46 .. ..
.. ~: . .
, . ...
, - ,, : ,~ , :, ,.,: ~ .
. .~ .
: . ~
.:
.~ .
rw~ - 3a -.; ~
1~376830 through reduction gears 48, 50 and 52. A pointer 54 attached to the end of shaft 46 is located over dial 56 to provide an operator with an indication of the altitude as measured by the aneroids 12 and 13.
A piezoelectrical transducer apparatus 58 which-is attached to the nousing 16 provides a controlled built-in vibration to compensate for static friction which can occur between the gears in the drive train of the altimeter 10.
In more detail, the piezoelectrical transducer apparatus 58 has a metal housing 60. The metal housing 60 has a base 62 and sidewalls 64 and 6~ ~hich extend from tne base 62. Tabs 68 and 70 radiate from the sidewalls 64 and 66 for engaging with a cover plate 72 to form a chamber 74 in the housing 60 for retaining a piezoelectrical crystal 76. The piezoelectrical crystal 76 is of a well known ceramic-type solution of lead-titanate and lead ~irconate. A layer of thermosetting resin or other insulator material 78 is located between the piezoelectrical crystal 76 and the metal housing 60 to prevent electrical communication from the piezoelectric crystal 76 to an electrical ground. First and second metal contacts 80 ' !
and 82, which are 1Ocated on opposite sides of the piezoelectrical crystal 76, are connected by lead lines 84 and 86, respectively, to the primary winding 88 of transformer 90 in a coupling circuit 92. The secondary winding 94 of the ; transformer 90 is located in an electrical supply circuit 9~.
The electrical supply circuit 96 includes a source of electrical voltage 98 connected to actuation switch 100. A first resistor 103 is located between switch 100 and a junction 104. The junction 104 is con-nec~ed to a capacitor 110 by a first lead lù6 and to a transistor diode 102 by a second lead 108. The transistor diode 102 is a single crystal silicon having four layers of distinctly different states of electrical conduction.
The transistor diode 102 has two stable states: (1) an "open" or high resistance state and (2) a "closed" or low resistance sta~e. The transistor diode 102 is switched from the first state to the second state by con-~07~830 .. . . .
trolling the voltage across it and passing current through it. A
resistor 114 is located between the transistor diode 102 and the secondary winding 94. The secondary winding 94 and the capacitor 110 are joined together at junction 116 and thereafter connected to electrical ground 118.
~ODE OF OPERATION OF THE INVENTION
The altimeter 10 is part of the equipment ehat a pilot of an aircraft must adjust and inspect as part of the preflight check out of the aircraft. Current barometric pressure must be obtained from control tower of an airport and fed into the altimeter 10 in order that the true ;~ 10 ground elevation is displayed in window 124 while the aircraft is on the ground. The current barometric pressure is transmitted into the altimeter throug~ knob 122 and displayed in window 120. Gear 126 which is sonnected `~ to knob 122 rotates gear 38 on shaft 34 to supply a corrective torque to `~ shaf~ 46 as gear 48 moves on stationary gear 44. This corrective torque ;
- causes the ground elevation indicated in window 124 to correspond to actual ground elevation of the airport.
Therea~ter, when the aircraft is airborne, the expansion and ~ contraction of the aneroids 12 and 13, in response to changes in pressure, - create a linear force which is transmitted into the sector gears 30 and 36 through shafts 18 and l9. Movement of sector gears 30 and 36 cause gear 32 to rotate and provide gear 44 with a torque indicative o~ the change in the pressure associated with a change in altitude. The rotation of gear 44 is modified through reduction gears 48, 50 and 52 to provide shaft 46 with sufficient torque to position pointer 54 at the elevation corresponding to that computered by the aneroids 12 and 13. !
When the aircraft is flying at a constant elevation, the entire gear train of the altimeter 10 from the aneroids 12 and 13 to the pointer 54 remains in a stationary position. Thereafter, with a change in elevation, the roeative torque re~uired to move shaft 46 must overcome static friction before pointer 54 moves. Such static friction causes the pointer 54 to _5_ appear to jump from one elevation to another instead of following a linear relationship.
In order to avoid stop-jump movement of the pointer 54, switch 100 is activated by the pilot in the preflight check out. With sw;tch 100 in the ON position, voltage from source 98 is communicated to junction 104.
This voltage is simultaneously transmitted to the transistor diode 102 and the capacitor 110. During this timD period, voltage is charging up the capacitor 110 and current flow through the transistor diode 102 is inhibited. When the voltage at the capacitor 110 reaches the breakover Yoltage of the transistor diode 102, the transistor diode 102 will switch to the closed or second operating condition. In this closed or second operating condition, the capacitor 110 is discharged to ground 118 as the current flows through resistor 11~ and the secondary winding 94 of the transformer 90. When the current level of the capacitor 110 approaches a complete discharge, the transistor diode 102 reverts to the open or f;rst operating condition and the charging up cycle begins again.
As the current flows through the secondary winding 94, a matching and amplified current signal is transmitted to the piezoelectrical crystal 76 through the coupling circuit 92. This amplified current signal causes the piezoelectrical crystal 76 to expand and exert a force through the insulator material 78 to housing 60. `~
Th~ duration of the amplified current signal in the matching circuit 92 follows the time period that the transistor diode 102 is in the closed condition. When the amplified current signal is removed from the piezoelectrical crystal 76, the expanded piezoelectrical crystal 76 reverts back to its original size.
The frequency of the amplified current signal in the matching circuit 92 is controlled by the charge-up time of capacitor 110 through resistor 103. A capacitor 110 is usually selected to control the output energy and frequency of the device.
.
~1~76830 By cyclicly applying the amplified current signal to the piezoelectrical crystal 76, the housing 60 sets up a vibratory force which is applied to housing 16 through base 62. This vibratory force is transmitted through housing 16 into shafts 34, 1~ and 19. The vibratory force which reaches gear 32 is sufficient to prevent static friction in the entire gear train conne:cted to pointer 54.
In addition, the insulation material 78 which surrounds the piezoelectric crystal 76 absorbs any noise created therein to prevent noise associated with the operation of the transducar apparatus 58 from ~ :~
being communicated into the cockpit of the aircraft.
' ~
"~ :;
.~ .
' ,` ~ ""
-7- ~
This invention relates to a vibratory apparatus for attenuating static friction in an altimeter havine an indicator driven by a low power sensor.
Since such low power sensors are responsive to the changes in pressure associated with changes in altitude, it is necessary that each incremen-t of torque developed by these sensors be transmitted to an ou-tput pointer without modifica-tion to assure that indicated altitude is the actual altitude.
Initially, it was thought that the vibrations produced ~ithin an aircraft would be sufficient to prevent static fric-tion. However, from observation it was observed that the indi-cator pointer movement was erratic, especially when the aircraft was operating on a smooth glide path.
Thereafter, it was suggested that a rotating eccentric vibrator or electrically driven thumper be attached to the hous-ing of the altimeter to attenuate static friction. While operating successfully to reduce static friction, such devices produce objectionable noise in the cockpit area of the aircraft, suffer from mechanical wearout, and thus fail to produce uniform results after a limited time period.
We have devised an altimeter with a piezoelectric transducer connected to the gear train of the altimeter which eliminates static friction without the creation of objectionable noise.
The present invention resides in an altimeter having a gear train driven by an altitude responsive member, with means for attenuating the frictional resistance of the gear train. According to the invention there is provided a housing connected to the gear train, the housing having a chamber located therein with a piezoelectrical transducer located in the chamber. Energy control means is provided for supplying the piezoelectrical transducer with cyclic electrical signals, rw~ - 2 - ~ -'` ~
1~)'76830 the cyclic electrical signals causing the physical dimensions of the piezoelectrical transducer to change and to transmit vibratory motion through the housing to the gear train to eliminate the effect of static friction thereon.
In a specific embodiment of the invention, the piezoelectric transducer, which is located in the housing, is encapsulated in a layer of insulating material. The insul-ating material, in addition to preventing the transmission of electrical energy between the pie~oelectric transducer and the housing, absorbs noise caused during the activation of the piezoelectric transducer by a cyclic electrical operational signal.
It is the object of this invention to provide an altimeter with a piezoelectric transducer connected to the gear train to attenuate static friction associated therewi-th.
In one embodiment of this invention there is provided ', an altimeter with a piezoelectric transducer responsive to an !:electrical signal derived from the operation of a four layer ~ ;
transistor diode device for attenuating static friction associa~
ted with a gear train through which a pressure responsive alti-tude sensor supplies an indicator with torque.
. These and other objects should be apparent from reading ~;
this specification and viewing the drawings. ~ ;
` BRIEF DESCRIPTIO~ OF THE DRAWI~G
The single figure in the drawing schematically illus-,- trates an altimeter and associated piezoelectrical transducer made according to the principles of this invention.
DETAILED DESCRIPTION OF THE INVENTION
The altimeter 10 shown in the drawing is similar to the altimeter disclosed in U.S. Patent No. 3,916,185.
The altimeter has a pressure responsive sensor with a first aneroid 12 ancl a second aneroid 13 located in a chamber 1~ of ''' ' ', .. 3~ , ~ rw/~!
- - .. ~ . . .~ . ;
10761~30 a housing 16. The first aneroid 12 is connected to a shaft 18 through an arm 20. Ends 22 and 24 of shaft 18 are journalled in jeweled bearings 26 and 28 which are pressed into openings in housing 16. A sector gear 30, which is fixed to shaft 18, engages gear 32 on the aneroid output shaft 34. The second aneroid 13 is similarly connectecl to a shaft 19 which retains sector gear 36. The outpu-t shaft 34 is carried through opening 38 in wall 40 of housing 16. A clriver gear 44, which is fixed .~ to the end of the output shaft 34, positions a barometric input gear 42 adjacent wall 40. The driver gear 44 is connected to output shaft 46 .. ..
.. ~: . .
, . ...
, - ,, : ,~ , :, ,.,: ~ .
. .~ .
: . ~
.:
.~ .
rw~ - 3a -.; ~
1~376830 through reduction gears 48, 50 and 52. A pointer 54 attached to the end of shaft 46 is located over dial 56 to provide an operator with an indication of the altitude as measured by the aneroids 12 and 13.
A piezoelectrical transducer apparatus 58 which-is attached to the nousing 16 provides a controlled built-in vibration to compensate for static friction which can occur between the gears in the drive train of the altimeter 10.
In more detail, the piezoelectrical transducer apparatus 58 has a metal housing 60. The metal housing 60 has a base 62 and sidewalls 64 and 6~ ~hich extend from tne base 62. Tabs 68 and 70 radiate from the sidewalls 64 and 66 for engaging with a cover plate 72 to form a chamber 74 in the housing 60 for retaining a piezoelectrical crystal 76. The piezoelectrical crystal 76 is of a well known ceramic-type solution of lead-titanate and lead ~irconate. A layer of thermosetting resin or other insulator material 78 is located between the piezoelectrical crystal 76 and the metal housing 60 to prevent electrical communication from the piezoelectric crystal 76 to an electrical ground. First and second metal contacts 80 ' !
and 82, which are 1Ocated on opposite sides of the piezoelectrical crystal 76, are connected by lead lines 84 and 86, respectively, to the primary winding 88 of transformer 90 in a coupling circuit 92. The secondary winding 94 of the ; transformer 90 is located in an electrical supply circuit 9~.
The electrical supply circuit 96 includes a source of electrical voltage 98 connected to actuation switch 100. A first resistor 103 is located between switch 100 and a junction 104. The junction 104 is con-nec~ed to a capacitor 110 by a first lead lù6 and to a transistor diode 102 by a second lead 108. The transistor diode 102 is a single crystal silicon having four layers of distinctly different states of electrical conduction.
The transistor diode 102 has two stable states: (1) an "open" or high resistance state and (2) a "closed" or low resistance sta~e. The transistor diode 102 is switched from the first state to the second state by con-~07~830 .. . . .
trolling the voltage across it and passing current through it. A
resistor 114 is located between the transistor diode 102 and the secondary winding 94. The secondary winding 94 and the capacitor 110 are joined together at junction 116 and thereafter connected to electrical ground 118.
~ODE OF OPERATION OF THE INVENTION
The altimeter 10 is part of the equipment ehat a pilot of an aircraft must adjust and inspect as part of the preflight check out of the aircraft. Current barometric pressure must be obtained from control tower of an airport and fed into the altimeter 10 in order that the true ;~ 10 ground elevation is displayed in window 124 while the aircraft is on the ground. The current barometric pressure is transmitted into the altimeter throug~ knob 122 and displayed in window 120. Gear 126 which is sonnected `~ to knob 122 rotates gear 38 on shaft 34 to supply a corrective torque to `~ shaf~ 46 as gear 48 moves on stationary gear 44. This corrective torque ;
- causes the ground elevation indicated in window 124 to correspond to actual ground elevation of the airport.
Therea~ter, when the aircraft is airborne, the expansion and ~ contraction of the aneroids 12 and 13, in response to changes in pressure, - create a linear force which is transmitted into the sector gears 30 and 36 through shafts 18 and l9. Movement of sector gears 30 and 36 cause gear 32 to rotate and provide gear 44 with a torque indicative o~ the change in the pressure associated with a change in altitude. The rotation of gear 44 is modified through reduction gears 48, 50 and 52 to provide shaft 46 with sufficient torque to position pointer 54 at the elevation corresponding to that computered by the aneroids 12 and 13. !
When the aircraft is flying at a constant elevation, the entire gear train of the altimeter 10 from the aneroids 12 and 13 to the pointer 54 remains in a stationary position. Thereafter, with a change in elevation, the roeative torque re~uired to move shaft 46 must overcome static friction before pointer 54 moves. Such static friction causes the pointer 54 to _5_ appear to jump from one elevation to another instead of following a linear relationship.
In order to avoid stop-jump movement of the pointer 54, switch 100 is activated by the pilot in the preflight check out. With sw;tch 100 in the ON position, voltage from source 98 is communicated to junction 104.
This voltage is simultaneously transmitted to the transistor diode 102 and the capacitor 110. During this timD period, voltage is charging up the capacitor 110 and current flow through the transistor diode 102 is inhibited. When the voltage at the capacitor 110 reaches the breakover Yoltage of the transistor diode 102, the transistor diode 102 will switch to the closed or second operating condition. In this closed or second operating condition, the capacitor 110 is discharged to ground 118 as the current flows through resistor 11~ and the secondary winding 94 of the transformer 90. When the current level of the capacitor 110 approaches a complete discharge, the transistor diode 102 reverts to the open or f;rst operating condition and the charging up cycle begins again.
As the current flows through the secondary winding 94, a matching and amplified current signal is transmitted to the piezoelectrical crystal 76 through the coupling circuit 92. This amplified current signal causes the piezoelectrical crystal 76 to expand and exert a force through the insulator material 78 to housing 60. `~
Th~ duration of the amplified current signal in the matching circuit 92 follows the time period that the transistor diode 102 is in the closed condition. When the amplified current signal is removed from the piezoelectrical crystal 76, the expanded piezoelectrical crystal 76 reverts back to its original size.
The frequency of the amplified current signal in the matching circuit 92 is controlled by the charge-up time of capacitor 110 through resistor 103. A capacitor 110 is usually selected to control the output energy and frequency of the device.
.
~1~76830 By cyclicly applying the amplified current signal to the piezoelectrical crystal 76, the housing 60 sets up a vibratory force which is applied to housing 16 through base 62. This vibratory force is transmitted through housing 16 into shafts 34, 1~ and 19. The vibratory force which reaches gear 32 is sufficient to prevent static friction in the entire gear train conne:cted to pointer 54.
In addition, the insulation material 78 which surrounds the piezoelectric crystal 76 absorbs any noise created therein to prevent noise associated with the operation of the transducar apparatus 58 from ~ :~
being communicated into the cockpit of the aircraft.
' ~
"~ :;
.~ .
' ,` ~ ""
-7- ~
Claims (7)
1. In an altimeter having a gear train driven by an altitude responsive member, means for attenuating the frictional resistance of said gear train comprising:
a housing connected to said gear train, said housing having a chamber located therein;
a piezoelectrical transducer located in said chamber; and energy control means for supplying said piezoelectrical trans-ducer with cyclic electrical signals, said cyclic electrical signals causing the physical dimensions of said piezoelectrical transducer to change and transmit vibratory motion through the housing to the gear train to eliminate the effect of static friction thereon.
a housing connected to said gear train, said housing having a chamber located therein;
a piezoelectrical transducer located in said chamber; and energy control means for supplying said piezoelectrical trans-ducer with cyclic electrical signals, said cyclic electrical signals causing the physical dimensions of said piezoelectrical transducer to change and transmit vibratory motion through the housing to the gear train to eliminate the effect of static friction thereon.
2. The altimeter, as recited in claim 1, wherein said attenu-ating means further includes:
insulator means for surrounding said piezoelectrical transducer, said insulator means isolating said piezoelectrical transducer to prevent the transmission of said cyclic electrical signals into said housing.
insulator means for surrounding said piezoelectrical transducer, said insulator means isolating said piezoelectrical transducer to prevent the transmission of said cyclic electrical signals into said housing.
3. The altimeter, as recited in claim 2, wherein said insulator means completely encapsulates said piezoelectrical transducer and fills said chamber to modify the amplitude of said vibratory motion.
4. The altimeter, as recited in claim 1, wherein said energy control means includes:
a source of voltage;
shaping means connected to said voltage for storing a pre-determined quantity of electrical charge in a fixed time period; and switch means responsive to said voltage and said predetermined quantity of electrical charge for allowing said predetermined quantity of electrical charge to be dissipated by flowing to an electrical ground and thereafter permit said shaping means to again store the predetermined quantity of electrical charge in said fixed time period.
a source of voltage;
shaping means connected to said voltage for storing a pre-determined quantity of electrical charge in a fixed time period; and switch means responsive to said voltage and said predetermined quantity of electrical charge for allowing said predetermined quantity of electrical charge to be dissipated by flowing to an electrical ground and thereafter permit said shaping means to again store the predetermined quantity of electrical charge in said fixed time period.
5. The altimeter, as recited in claim 4, wherein said energy control means includes:
coupling means located between said switch means and the electrical ground for deriving said cyclic electrical signal from the flow of said predetermined quantity of electrical current to the electrical ground.
coupling means located between said switch means and the electrical ground for deriving said cyclic electrical signal from the flow of said predetermined quantity of electrical current to the electrical ground.
6. The altimeter, as recited in claim 5, wherein said coupling means includes:
a transformer with a primary winding located between said switch means and the electrical ground; and a secondary winding in series with the piezoelectrical transducer.
a transformer with a primary winding located between said switch means and the electrical ground; and a secondary winding in series with the piezoelectrical transducer.
7. The altimeter, as recited in claim 6, wherein said energy control means includes:
a resistor located between said switch means and said electrical ground to limit the flow of electrical current through said switch means.
a resistor located between said switch means and said electrical ground to limit the flow of electrical current through said switch means.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/755,277 US4052902A (en) | 1976-12-29 | 1976-12-29 | Static friction free altimeter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1076830A true CA1076830A (en) | 1980-05-06 |
Family
ID=25038471
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA291,416A Expired CA1076830A (en) | 1976-12-29 | 1977-11-22 | Static friction free altimeter |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4052902A (en) |
| CA (1) | CA1076830A (en) |
| DE (1) | DE2758732A1 (en) |
| FR (1) | FR2376398A1 (en) |
| GB (1) | GB1540990A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0413142A3 (en) * | 1989-08-18 | 1991-10-02 | Sarcem Automation | Altimeter |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3387257A (en) * | 1967-01-25 | 1968-06-04 | Branson Instr | Pulse circuit for pulse echo ultrasonic testing |
| GB1243270A (en) * | 1969-12-22 | 1971-08-18 | John Francis De Mayo | Electromagnetically operated tapping device |
| US3831451A (en) * | 1973-01-26 | 1974-08-27 | Int Dynamics Corp | Means for avoiding static friction |
-
1976
- 1976-12-29 US US05/755,277 patent/US4052902A/en not_active Expired - Lifetime
-
1977
- 1977-11-22 CA CA291,416A patent/CA1076830A/en not_active Expired
- 1977-12-14 GB GB52055/77A patent/GB1540990A/en not_active Expired
- 1977-12-23 FR FR7739040A patent/FR2376398A1/en active Granted
- 1977-12-29 DE DE19772758732 patent/DE2758732A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| DE2758732A1 (en) | 1978-07-13 |
| FR2376398A1 (en) | 1978-07-28 |
| GB1540990A (en) | 1979-02-21 |
| FR2376398B1 (en) | 1980-08-22 |
| US4052902A (en) | 1977-10-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |